1. Field of the Invention
The present invention relates to an imaging device incorporated in electronic equipment, such as a digital still/movie camera, a cellular-phone, and so on. Especially, it relates to a signal process associated with a color reproduction.
2. Description of the Related Art
In an imaging device, a primary color filter such as R, G, and B color filter or a complementary color filter such as Ye, CY, Mg, and G color filter is arranged on a photo-sensitive area of an image sensor. The color filter has R, G, and B color elements arrangement in a checkered configuration such that the color elements are opposite to pixels arranged in the photo-sensitive area. Light, reflected on an object, passes through the color filter so that image-pixel signals composed of color signals corresponding to the color elements, are generated and read from the image sensor. The image-pixel signals are subjected to a color conversion process or a matrix computation to produce image signals depending upon the standard color space defined by the colorimetry. Consequently, video signals such as NTSC signals are output to peripheral apparatus such as a monitor.
In a digital camera, various arrangements of the color elements, or color conversion processes has been attempted to adequately reproduce an objective color as accurately as possible, namely, to reproduce the objectives color so as to be colors that are perceived or visualized in real lire. For example, a color element “G′”, which has a relative spectral response property (characteristics) close to that of the Green color element (G), is arranged in the color filter instead of Green color element “G”, so that corrected or modified red color signals for the color Red, which makes a colorimetrical range of reproduced color broad, are generated. Another color filter is composed of four color elements, “R”, “G”, and “B” color elements and a color element that has a different spectral transmission property. In this case, R, G, and B primary color signals, corresponding to tristimulus values, are generated by a “4×3” matrix computation. The four color elements reproduce an objective color while reducing noise.